Abstract: A power conversion apparatus includes a first power conversion circuit including a first switching element, a second power conversion circuit including a second switching element, a DC conductor which is provided in the first power conversion circuit and supplies a DC power to the first power conversion circuit, and a connection conductor which is provided in the first power conversion circuit, has a length having an inductance for inhibiting a flow of a ripple current caused by switching of the second switching element of the second power conversion circuit, and connects the DC conductor and the second power conversion circuit.

Abstract: Wiring between semiconductor modules and a direct current power supply circuit, which construct a three-level power conversion apparatus, is made to be low inductance, so that reduction in size and cost can be attained easily. In cases where a connection is made between direct current power supplies (electrolytic capacitors) 25, 26 and IGBT modules 16 through 18 of a three-level inverter, a wiring conductor for a bi-directional switch part is divided into three conductors 35, 42, 43 or two conductors 35, 42 on a same surface, and these conductors are sandwiched by a P conductor 33 and an N conductor 37, which are arranged at outer sides thereof, respectively, through insulating materials, so that a three-layer wiring structure of a sealed structure is formed. As a result of this, wiring inductance can be made small even with a small number of laminated layers, so that the reduction in size and cost of the apparatus as a whole is achieved.

Abstract: The disk drive apparatus of the present invention has an optical pickup that jumps a track to perform track jumping when a jumping voltage is impressed, and that traces a track by performing brake operation when a braking voltage is applied, and actuator that drives the optical pickup, a signal processing part that performs focus and tracking control with respect to the optical pickup, a movement time measurement part that measures the movement time when a light beam emitted from the optical pickup is moved to cross a track to a required track, a voltage control part that uses the results of measurement to generate parameters and a voltage value that is applied to the actuator, a storage part that stores voltage value that is generated by the voltage value setting part, and that after a disk is loaded, first stores data of that disk in the storage part and uses those data values according to the track jump operation.

Abstract: An optical disk drive for recording and reproducing information on an optical disk medium includes a servo circuit for controlling tracking of a light beam on a predetermined track and a servo circuit for controlling focus of the light beam on the disk surface. The disk surface is divided into a plurality of regions, and calibration values for adjusting the servo circuits are determined in each region. The calibration values are stored in a memory and are used to adjust the servo circuits during tracking on a predetermined track. The calibration values include tracking offset values, focus offset values, servo deviation threshold values and sensor gain values. A number of techniques are disclosed for automatically determining the calibration values.

Abstract: An optical head for optical recording and reproducing system comprising a light source, a first optical means for introducing a light beam from the light source into a guide groove formed in a recording surface of an information carrier, and a second optical means for separating a reflected light beam reflected from the guide groove from the light beam from the light source. The optical head also comprises an optical element having formed thereon at its center a cylindrical surface and on both sides slanted surfaces for dividing the reflected light beam into three, and a light receiving element having at least three light receiving units for receiving the respective light beams divided into three by the optical element.